Nak Cassette Observation - BX-125

[OldiesButGoodies]

So I mentioned I spent some time rebelting and cleaning a Nak deck last night,  a BX-125.  Now, I have a bunch of decks in my listening room,  including some that lived several rungs higher in the product line up than the BX-125.  I have three BX-125s in the collection - well now I have two because I sold one last week - they sounded good but nothing spectacular.  This one I had not tried until today because it needed work. 

Holy tapes, batman, this thing sounds better than any of the others in the room (well,  in playback anyway, have not tested recording).  It is amazing.  I guess I ran into a properly calibrated Nak by luck (I have heard from other cassette addicts that almost all decks came from the factory needing calibration... etc. etc.).  So now I am excited about the possibility of getting some of my other Naks to shine like this one using the calibration tapes (those are making their way to me from Spain,  via slow boat it seems). 

 

Cap Cassette Deek

PS:  Could also be that the KT-120s are making everything sound better   

[MacGeek]

OBG-I thought recording test signals for proper calibration was required and recall a dealer who calibrated decks for specific tape types (TDK SA was always my choice).  I calibrated my CR-3A using test signals from a CD (400 and 15khz). How is that accomplished with test tapes?

[OldiesButGoodies]

Hi MG

The issue as I understand it,  is having a reliable reference to adjust the deck with. I assume you record the test signals from the CD on a deck known to be calibrated and then use that on the CR3a? That is the challenge, as I see it.  The test tapes give you a known reference to adjust from while the deck is in playback.  Speed adjustment requires a reference tape recorded at 3khz by a deck that is operating perfectly, for example. 

I may give you a call to understand how you do it with external signals...  (should have done that earlier, you hinted that you were going to adjust the CR3 when we bought the decks)

Anders - can you comment on this?

Thanks

Pepe

[Anders]

Trouble with reference/calibration tapes is they are only good for a relatively short period of time and they are expensive to replace.
I recorded my own reference tapes.

[OldiesButGoodies]

Anders:

I guess I should have done a beter job of framing the question. 

Klaus uses a test CD to calibrate his decks.  That is the source of his 15Khz, 1khz and 400hz signals.  I was under the impression that the only way to do that was to use a calibrated deck to create tapes recorded with those signals, to complete the steps leaid out in the pictures below from the instruction manual. 

Is there a way to do it w/o tapes?

Thanks

Pepe

PS:  McGeek - called you but you were out,  will ring again later...

 

[papabearjew]

There is a signal generator I downloaded for free cleverly called "Signal Generator" by radonsoft. It generates sine waves from 20-20kHz, pink noise, and white noise. I downloaded it onto my Android devices. Very handy for many applications. Tap off the headphone jack and feed it into anything you ant to. The pink noise is very useful for fine tuning bias by ear on a tape deck.
Also an FWI for Nak CR-3 and CR-4 owners. There is a simple mod that corrects a grounding issue that noticeably improves sound. It's a simple matter of cutting a trace on the power supply pcb and joining the two pins at C373 together. Very detailed instructions and photos are available at
Www.tapeheads.netshowthread.php?t=21671. It's worth doing. Makes an awesome deck sound even better. Any questions let me know.

[audiott]

What is the allure to cassette decks and reel to reel.  Just curious.

[OldiesButGoodies]

Just the fun of repairing them and recording music,  which requires some skill.  I would argue that even some digital-source recordings laid on r2r sound better on that format, less harsh, more realistic.  And I can hi half price books or an number of similar locations and come out with a bunch of cassettes, for little dough. 

I also listen to CDs, SACDs, DVD-A, and of course vinyl. 

[audiott]

Always wondered.  Thanks for the response. Repairing is not my strong point. I should probably stay away from it!

[MacGeek]

I am focused primarily on bias and don't have the information/tools to check speed, dolby level, distrotion and other adjustments.  For that, my equipment goes to the shop.  For bias, the tape (or tape formulation) to be biased has to be loaded in the deck.  The high end machines with front panel bias adjustments simply move the internal bias pots to the front panel and adjust bias to specific tapes.  I don't worry much about speed, generally having the source for comparison (and speed is only an issue if record and plav back occur on different decks).

[OldiesButGoodies]

Ok - this explains the confusion. 

In my case i am trying to go a bit further and try to do some of the work an experienced tech would do, making electrical adjustments and head height, azimuth tweaks etc. using the output of the cassette connected to an oscilloscope simulator on the PC and/or the volt meter.

So this clear the confusion...  Thanks

[MacGeek]

OK, that means I need to learn some stuff from you when you have time.